/*
* Metadata - jQuery plugin for parsing metadata from elements
*
* Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
*
* Dual licensed under the MIT and GPL licenses:
*   http://www.opensource.org/licenses/mit-license.php
*   http://www.gnu.org/licenses/gpl.html
*
* Revision: $Id: jquery.metadata.js 3640 2007-10-11 18:34:38Z pmclanahan $
*
*/

/**
* Sets the type of metadata to use. Metadata is encoded in JSON, and each property
* in the JSON will become a property of the element itself.
*
* There are four supported types of metadata storage:
*
*   attr:  Inside an attribute. The name parameter indicates *which* attribute.
*          
*   class: Inside the class attribute, wrapped in curly braces: { }
*   
*   elem:  Inside a child element (e.g. a script tag). The
*          name parameter indicates *which* element.
*   html5: Values are stored in data-* attributes.
*          
* The metadata for an element is loaded the first time the element is accessed via jQuery.
*
* As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
* matched by expr, then redefine the metadata type and run another $(expr) for other elements.
* 
* @name $.metadata.setType
*
* @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("class")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from the class attribute
* 
* @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("attr", "data")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a "data" attribute
* 
* @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
* @before $.metadata.setType("elem", "script")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a nested script element
* 
* @example <p id="one" class="some_class" data-item_id="1" data-item_label="Label">This is a p</p>
* @before $.metadata.setType("html5")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a series of data-* attributes
*
* @param String type The encoding type
* @param String name The name of the attribute to be used to get metadata (optional)
* @cat Plugins/Metadata
* @descr Sets the type of encoding to be used when loading metadata for the first time
* @type undefined
* @see metadata()
*/

(function ($) {

    $.extend({
        metadata: {
            defaults: {
                type: 'class',
                name: 'metadata',
                cre: /({.*})/,
                single: 'metadata'
            },
            setType: function (type, name) {
                this.defaults.type = type;
                this.defaults.name = name;
            },
            get: function (elem, opts) {
                var settings = $.extend({}, this.defaults, opts);
                // check for empty string in single property
                if (!settings.single.length) settings.single = 'metadata';

                var data = $.data(elem, settings.single);
                // returned cached data if it already exists
                if (data) return data;

                data = "{}";

                var getData = function (data) {
                    if (typeof data != "string") return data;

                    if (data.indexOf('{') < 0) {
                        data = eval("(" + data + ")");
                    }
                }

                var getObject = function (data) {
                    if (typeof data != "string") return data;

                    data = eval("(" + data + ")");
                    return data;
                }

                if (settings.type == "html5") {
                    var object = {};
                    $(elem.attributes).each(function () {
                        var name = this.nodeName;
                        if (name.match(/^data-/)) name = name.replace(/^data-/, '');
                        else return true;
                        object[name] = getObject(this.nodeValue);
                    });
                } else {
                    if (settings.type == "class") {
                        var m = settings.cre.exec(elem.className);
                        if (m)
                            data = m[1];
                    } else if (settings.type == "elem") {
                        if (!elem.getElementsByTagName) return;
                        var e = elem.getElementsByTagName(settings.name);
                        if (e.length)
                            data = $.trim(e[0].innerHTML);
                    } else if (elem.getAttribute != undefined) {
                        var attr = elem.getAttribute(settings.name);
                        if (attr)
                            data = attr;
                    }
                    object = getObject(data.indexOf("{") < 0 ? "{" + data + "}" : data);
                }

                $.data(elem, settings.single, object);
                return object;
            }
        }
    });

    /**
    * Returns the metadata object for the first member of the jQuery object.
    *
    * @name metadata
    * @descr Returns element's metadata object
    * @param Object opts An object contianing settings to override the defaults
    * @type jQuery
    * @cat Plugins/Metadata
    */
    $.fn.metadata = function (opts) {
        return $.metadata.get(this[0], opts);
    };

})(jQuery);